Vitamins, minerals and supplements

Vitamins and minerals are essential nutrients that your body needs in small amounts to work properly.

Most people should be able to get all the nutrients they need by eating a varied and balanced diet. If you choose to take vitamin and mineral supplements, be aware that taking too much or taking them for too long can cause harmful effects.

The pages in this section contain all the advice and information that adults need about the vitamins, minerals and trace elements that are essential for health, including:

what they do

how much you need

what happens if you have too much

safety advice about supplements

What are vitamins?

There are two types of vitamins: fat-soluble and water-soluble.

Fat-soluble vitamins

Fat-soluble vitamins are found mainly in fatty foods such as animal fats including butter and lard, vegetable oils, dairy foods, liver and oily fish.

While your body needs these vitamins every day to work properly, you do not need to eat foods containing them every day.

This is because, if your body does not need these vitamins immediately, it stores them in your liver and fatty tissues for future use. These stores can build up so they are there when you need them. However, if you have much more than you need, fat-soluble vitamins can be harmful.

Water-soluble vitamins

Water-soluble vitamins are not stored in the body, so you need to have them more frequently.

If you have more than you need, your body gets rid of the extra vitamins when you urinate. Because the body does not store water-soluble vitamins, these vitamins are generally not harmful.

Water-soluble vitamins are found in fruit, vegetables and grains. Unlike fat-soluble vitamins, they can be destroyed by heat or by being exposed to the air. They can also be lost in water used for cooking.

This means that by cooking foods, especially boiling them, we lose many of these vitamins. The best way to keep as much of the water-soluble vitamins as possible is to steam or grill these foods, rather than boil them.

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Vitamin A is also known as retinol. It has several important functions, such as:

strengthening immunity against infections

helping vision in dim light

keeping skin and the linings of some parts of the body, such as the nose, healthy

Good sources of vitamin A

Good sources of vitamin A include:

cheese

eggs

oily fish, such as mackerel

milk

fortified low-fat spreads

yoghurt

Liver is a particularly rich source of vitamin A. Do not eat liver if you are pregnant (see box, right).

How much vitamin A do I need?

The amount of vitamin A adults need is:

0.7mg a day for men

0.6mg a day for women

You should be able to get all the vitamin A you need from your daily diet.

Any vitamin A that your body does not need immediately is stored for future use. This means you do not need it every day.

What happens if I take too much vitamin A?

According to some research, having more than an average of 1.5mg a day of vitamin A over many years may affect your bones, making them more likely to fracture when you are older.

Older people, particularly women, are already at risk of osteoporosis. This is where your bone density reduces and you have a higher risk of fractures.

If you eat liver or liver pâté once a week, you may be getting more than a daily average of 1.5mg of vitamin A.

If you do not get enough vitamin D, you could be more at risk of the harmful effects of too much vitamin A. People who may be particularly short of vitamin D include:

all pregnant and breastfeeding women

all people aged 65 and over

people who are not exposed to much sun, for example those who cover up their skin for cultural reasons, or those who are housebound or confined indoors for long periods

people with darker skin such as people of African-Caribbean and South Asian origin

Many multivitamins contain vitamin A. Other supplements, such as fish liver oil, are also high in vitamin A. If you take supplements containing vitamin A, make sure your daily intake of vitamin A from food and supplements does not exceed 1.5mg. If you eat liver every week, do not take supplements that contain vitamin A.

If you are pregnant, do not take multivitamins containing vitamin A.

If you are pregnant or thinking of having a baby:

Do not take supplements containing vitamin A, including fish liver oil, except if you are advised to by your GP

Do not eat liver or liver products, such as pâté, because these are very high in vitamin A

Women who have been through the menopause and older men, who are more at risk of osteoporosis, should avoid having more than 1.5mg of vitamin A a day from food and supplements. This means:

not eating liver or liver products, such as pâté, more than once a week, or having smaller portions of these

taking no more than 1.5mg of vitamin A a day in supplements (including fish liver oil) if you do not eat liver or liver products

not taking any supplements containing vitamin A (including fish liver oil) if you eat liver once a week

Having an average of 1.5mg a day or less of vitamin A from diet and supplements combined is unlikely to cause any harm.

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If you are pregnant

Having large amounts of vitamin A can harm your unborn baby. Therefore, if you are pregnant or thinking of having a baby, do not eat liver or liver products, such as pâté, because these are very high in vitamin A.

Also, do not take supplements that contain vitamin A. Ask your GP or midwife if you would like more information.

How much folate do I need?

Folate cannot be stored in the body, so you need it in your diet every day.

Most people should be able to get the amount they need by eating a varied and balanced diet.

However, if you are pregnant or thinking of having a baby, take a daily 0.4mg (400 microgram) of folic acid supplement from the time you stop using contraception until the 12th week of pregnancy. This is to help prevent birth defects of the central nervous system, such as spina bifida, in your baby.

Women who have had a pregnancy affected by a neural tube defect need to take 5mg of folic acid each day until the 12th week of pregnancy. This is available on prescription from your GP. Women with diabetes and those taking anti-epileptic medicines should speak to their GP for advice.

Taking a high dose of folic acid can cause..

If you do not get enough vitamin B12, taking doses of folic acid higher than 1mg can disguise the effects of this.

An early symptom of vitamin B12 deficiency is anaemia. However, taking large amounts of folic acid treats the anaemia without treating the B12 deficiency. If a vitamin B12 deficiency is not noticed, it can eventually damage the nervous system.

This is particularly a concern for older people because it becomes more difficult to absorb vitamin B12 as you get older.

Women who are not pregnant or planning for a baby should be able to get all the folate they need by eating a varied and balanced diet.

If you are taking folic acid supplements, it is important not to take too much because this could be harmful.

Taking 1mg (1,000 micrograms) or less a day of folic acid supplements is unlikely to cause any harm.

Good sources of vitamin D

Most of our vitamin D comes from sunlight on our skin. The vitamin forms under the skin in reaction to sunlight. The best source is summer sunlight. However, if you are out in the sun, take care not to turn red or get burnt.

Vitamin D is also found in a small number of foods. Good food sources are:

oily fish, such as salmon and sardines

eggs

fortified fat spreads

fortified breakfast cereals

powdered milk

How much vitamin D do I need?

You do not need vitamin D in your diet every day. This is because any of the vitamin your body does not need immediately is stored for future use.

However, the Food Safety Authority and the Health Service Executive recommend that all babies 0 to 12 months should receive a vitamin D supplement.Vitamin D3 is the preferred form of the supplement for infants. Products which contain other vitamins as well as vitamin D should not be used.

What happens if I take too much vitamin D?

Taking high doses of vitamin D for long periods of time could weaken your bones.

Most people should be able to get the vitamin D they need by eating a varied and balanced diet and by getting some sun. If you take vitamin D supplements, do not take too much.

Taking 25 micrograms (0.025mg) or less a day of vitamin D supplements is unlikely to cause any harm.

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Vitamin K has several important functions. For example, it is needed for blood clotting, which means it helps wounds heal properly.

There is increasing evidence that vitamin K is also needed to help build strong bones.

Good sources of vitamin K

Vitamin K is found in:

green leafy vegetables, such as broccoli and spinach

vegetable oils

cereals

Small amounts can also be found in meat and dairy foods.

As well as getting vitamin K from food, we also get it from our own bodies as it is produced by bacteria in the bowel.

How much vitamin K do I need?

Adults need approximately 0.001mg a day of vitamin K for each kilogram of their body weight.

For example, someone who weighs 65kg would need 0.065mg a day of vitamin K, while a person who weighs 75kg would need 0.075mg a day.

You should be able to get all the vitamin K you need by eating a varied and balanced diet.

Any vitamin K that your body does not need immediately is stored in the liver for future use, so you do not need it in your diet every day.

What happens if I take too much vitamin K?

There is not enough evidence to know what the effects might be of taking high doses of vitamin K supplements each day. If you take vitamin K supplements, do not take too much because this might be harmful.

Taking 1mg or less of vitamin K supplements a day is unlikely to cause any harm.

Beta-carotene

Beta-carotene gives yellow and orange fruit and vegetables their colour. It is turned into vitamin A in the body, so it can perform the same functions in the body as vitamin A.

Good sources of beta-carotene

The main food sources of beta-carotene are:

yellow and green (leafy) vegetables, such as spinach, carrots and red peppers

yellow fruit such as mango, melon and apricots

How much beta-carotene do I need?

You should be able to get the amount of beta-carotene you need from your daily diet.

What happens if I take too much beta-carotene?

Beta-carotene supplements have been found to increase the risk of lung cancer developing in smokers and in people who have been heavily exposed to asbestos at work.

It is possible that taking large amounts of beta-carotene supplements would also increase the risk of cancer in other people.

Some research suggests that having large amounts of vitamin A over a long time may affect people's bones and make them more likely to fracture when they are older. However, beta-carotene does not have this effect. This is because the body's conversion of beta-carotene into vitamin A is not very efficient, so it is unlikely to result in high levels of vitamin A in the body.

What does the Department of Health advise?

You should be able to get the amount of beta-carotene you need by eating a varied and balanced diet. If you decide to take beta-carotene supplements, it is important not to take too much because this could be harmful.

Do not take more than 7mg of beta-carotene supplements a day. However, continue taking a higher dose if advised to do so by a doctor.

People who smoke or who have been exposed to asbestos are advised not to take any beta-carotene supplements.

There is no evidence that the beta-carotene we get from food is harmful.

Boron

Boron is a trace element. It is thought to help the body make use of glucose, fats, oestrogen and other minerals, such as calcium, copper and magnesium, in the food we eat.

Good sources of boron

Boron is found widely in the environment, in the oceans, rocks, soils and plants. Food sources of boron include:

green vegetables

fruit

nuts

How much boron do I need?

You should be able to get all the boron you need from your daily diet.

What happens if I take too much boron?

Taking high doses of boron for long periods may reduce fertility in men.

What does the Department of Health advise?

You should be able to get all the boron you need by eating a varied and balanced diet. If you take supplements containing boron, do not take too much because this could be harmful.

Taking 6mg or less of boron supplements a day is unlikely to cause any harm.

Chromium

Chromium is a trace element that is thought to influence how the hormone insulin behaves in the body. This means that chromium may affect the amount of energy we get from food.

Good sources of chromium

Chromium is found widely in the environment, in the air, water and soil, and in plants and animals.

Good food sources of chromium include:

meat

wholegrains, such as wholemeal bread and whole oats

lentils

spices

How much chromium do I need?

Adults need at least 0.025mg of chromium a day.

You should be able to get all the chromium you need by eating a varied and balanced diet.

What happens if I take too much chromium?

There is not enough evidence to know what the effects might be of taking high doses of chromium each day.

What does the Department of Health advise?

You should be able to get all the chromium you need by eating a varied and balanced diet.

If you take chromium supplements, do not take too much because this might be harmful.

Having 10mg or less a day of chromium from food and supplements is unlikely to cause any harm.

Cobalt

Cobalt is a trace element that forms part of the structure of vitamin B12.

Good sources of cobalt

Cobalt is found widely in the environment. Good food sources of cobalt include:

fish

nuts

green leafy vegetables, such as broccoli and spinach

cereals, such as oats

How much cobalt do I need?

You should be able to get all the cobalt you need from your daily diet.

Cobalt is a major part of the structure of vitamin B12. Therefore, if you get enough vitamin B12, you will also get enough cobalt.

What happens if I take too much potassium?

What does the Department of Health advise?

You should be able to get all the potassium you need by eating a varied and balanced diet. If you take potassium supplements, do not take too much because this could be harmful.

Taking 3,700mg or less of potassium supplements a day is unlikely to cause any harm.

However, older people may be more at risk of harm from potassium. This is because as we get older, our kidneys may become less able to remove potassium from our blood. Therefore, older people should not have potassium supplements unless advised to take them by a doctor.

Selenium

Selenium is a trace element that plays an important role in our immune system's function and in reproduction. It also helps prevent damage to cells and tissues.

Good sources of selenium

Selenium is found widely in the environment. Good food sources include:

brazil nuts

bread

fish

meat

eggs

How much do I need?

The amount of selenium you need is:

0.075mg a day for men

0.06mg a day for women

If you eat meat, fish or nuts, you should be able to get all the selenium you need from your daily diet.

What happens if I take too much selenium?

Too much selenium causes selenosis, a condition that in its mildest form can lead to loss of hair, skin and nails.

What does the Department of Health advise?

You should be able to get all the selenium you need by eating a varied and balanced diet that includes meat, fish or nuts. If you take selenium supplements, it is important not to take too much because this could be harmful.

Taking 0.35mg or less a day of selenium supplements is unlikely to cause any harm.

Silicon

Silicon is a mineral that has two main functions. It:

helps keep bones healthy

helps keep connective tissues healthy (connective tissue gives support and structure to other tissue and organs)

Good sources of silicon

Silicon is found in high levels in grains such as oats, barley and rice. It is also found in fruit and vegetables.

How much silicon do I need?

You should be able to get all the silicon you need from your daily diet.

What happens if I take too much silicon?

There is not enough evidence to know what the effects might be of taking high doses of silicon supplements each day.

What does the Department of Health advise?

You should be able to get all the silicon you need by eating a varied and balanced diet. If you take silicon supplements, it is important not to take too much because this might be harmful.

Taking 700mg or less of silicon supplements a day is unlikely to cause any harm.

Sodium chloride (salt)

Sodium chloride is commonly known as salt. Sodium and chloride both help keep the level of fluids in the body balanced.

Chloride helps the body digest food because it is an essential component of the juices in the stomach and intestines.

Sources of salt

Salt is found naturally at low levels in all foods, but some salt is added to many processed foods such as:

ready meals

meat products, such as bacon

some breakfast cereals

cheese

some tinned vegetables

some bread

savoury snacks

How much salt do I need?

You should have no more than 6g of salt (2.4g of sodium) a day. However, on average people eat 9.5g of salt (about 3.7g of sodium) a day.

A few practical tips for cutting down on salt include:

Check food labels and choose foods with less salt.

Choose tinned vegetables and pulses with no added salt.

Use sauces, such as soy sauce, sparingly because these are often high in salt.

Eat fewer salty snacks, such as crisps and salted nuts.

Add less salt when cooking. Use herbs and spices for flavour instead.

Choose low-salt stock cubes, or make your own stock.

Taste your food first and do not automatically add extra salt.

What happens if I have too much salt?

Having too much salt is linked to an increase in blood pressure (hypertension), which raises your risk of a stroke and heart attack.

What does the Department of Health advise?

On average, we eat 3.5g more salt than we should each day.

The Department of Health advises people to cut down on salt and that sodium chloride should not be used in supplements.

Sulphur

Sulphur is a mineral that is involved in many different processes. For example, it helps make tissues such as cartilage.

Sources of sulphur

Sulphur is found naturally in many different forms in all foods. It is also used in the form of sulphates and sulphites as food additives in some processed foods.

How much sulphur do I need?

You can get all the sulphur you need from your daily diet.

What does the Department of Health advise?

You can get all the sulphur you need by eating a varied and balanced diet.

Zinc

Zinc is a trace element that has several important functions. For example it:

helps make new cells and enzymes

helps us process carbohydrate, fat and protein in food

helps with the healing of wounds

Good sources of zinc

Zinc is found widely in the environment. Good food sources of zinc include:

meat

shellfish

milk

dairy foods, such as cheese

bread

cereal products, such as wheat germ.

How much zinc do I need?

The amount of zinc you need is about:

5.5-9.5mg a day for men

4-7mg a day for women

You should be able to get all the zinc you need from your daily diet.

What happens if I take too much zinc?

Taking high doses of zinc reduces the amount of copper the body can absorb. This can lead to anaemia and to weakening of the bones.

What does the Department of Health advise?

You should be able to get all the zinc you need by eating a varied and balanced diet. If you take zinc supplements, it is important not to take too much because this could be harmful.

Do not take more than 25mg of zinc supplements a day. However, continue taking a higher dose if advised to by a doctor.